Lack of Protocol for Rooftop Rescues.

Civilians at or above the impact zone in the North Tower had the smallest hope of survival. Once the plane struck, they were prevented from descending because of damage to or impassable conditions in the building's three stairwells. The only hope for those on the upper floors of the North Tower would have been a swift and extensive air rescue. Several factors made this impossible. Doors leading to the roof were kept locked for security reasons, and damage to software in the security command station prevented a lock release order from taking effect. Even if the doors had not been locked, structural and radiation hazards made the rooftops unsuitable staging areas for a large number of civilians; and even if conditions permitted general helicopter evacuations-which was not the case-only several people could be lifted at a time.

The WTC lacked any plan for evacuation of civilians on upper floors of the WTC in the event that all stairwells were impassable below.